﻿    <p>
      The <em>IfcFacetedBrepWithVoids</em> is a specialization of a
      faceted B-rep which contains one or more voids in its
      interior. The voids are represented as closed shells which
      are defined so that the shell normal point into the void.
    </p>
    <blockquote class="note">
      NOTE&nbsp; Entity adapted from
      <strong>brep_with_voids</strong> AND
      <strong>faceted_brep</strong> defined in ISO 10303-42.
    </blockquote>
    <blockquote class="history">
      HISTORY&nbsp; New entity in IFC1.0
    </blockquote>
    <blockquote class="change-ifc2x4">
      IFC4 CHANGE&nbsp; Subtyping changed from
      <em>IfcManifoldSolidBrep</em> to <em>IfcFacetedBrep</em> with
      upward compatibility for file based exchange.
    </blockquote>
    <p>
      &nbsp;
    </p>
    <p class="spec-head">Informal Propositions:</p>
    <ol>
      <li>Each void shell shall be disjoint from the outer shell
      and from every other void shell
      </li>
      <li>Each void shell shall be enclosed within the outer shell
      but not within any other void shell. In particular the outer
      shell is not in the set of void shells
      </li>
      <li>Each shell in the <em>IfcManifoldSolidBrep</em> shall be
      referenced only once.
      </li>
      <li>All the bounding loops of all the faces of all the shells
      in the <em>IfcFacetedBrep</em> shall be of type
      <em>IfcPolyLoop</em>.
      </li>
    </ol>